1. Field of the Invention
The invention relates in general to a thin-film transistor array substrate typically used in a transflective liquid crystal display, and more particularly, to a thin-film transistor array substrate of which the pixel electrodes of the transparent sub-pixels and reflective sub-pixels are electrically connected to different transistors.
2. Related Art of the Invention
The advancement of multimedia basically results from the progress of semiconductor device or display apparatus design. Conventional display apparatus such as the cathode ray tube (CRT) have dominated the market for decades due to its excellent display quality and economics. However, issues of space utilization and power consumption exist in cathode ray tubes. Therefore, the light, thin, short and small thin-film transistor liquid crystal display (TFT LCD) with high display quality and low power consumption has gradually replaced the cathode ray tube to become main stream in the market. If the fabrication cost of the thin-film transistor liquid crystal display can be reduced, the market share and competition will be greatly increased. Characterized by the display method, the liquid crystal display can be divided into the transmissive type liquid crystal display, the reflective type liquid crystal display, and the transreflective type liquid crystal display.
In U.S. Pat. No. 6,195,140, a transreflective type liquid crystal display is described. FIGS. 1 and 2 show the top view and cross sectional view of the conventional transreflective type liquid crystal display. In FIG. 1, a thin-film transistor substrate 100 including a thin-film transistor 102 and a pixel 104 is shown. The pixel 104 has a reflective region R and a transparent region T. The reflective region R of the pixel 104 consists of a reflective pixel electrode 106 made of aluminum material, and the transparent region T of the pixel 104 consists of a transparent pixel electrode 108 made of material such as indium tin oxide. Each thin-film transistor 102 is used to control a pixel 104 including one reflective pixel electrode 106 and a transparent pixel electrode 108.
FIG. 2 shows the cross sectional view cutting along the line I-II of FIG. 1. The thin-film transistor 102 has a source/drain region 12 electrically connected to the transparent pixel electrode 108. A molybdenum layer 110 is further formed between the transparent pixel electrode 108 and the reflective pixel electrode 106. While fabricating the pixel 104, formation of the molybdenum layer 110 prevents corrosion problems caused by electrochemical reaction.
However, in the conventional thin-film transistor array substrate, the molybdenum layer, though improving the corrosion problem caused by electrochemical reaction, increases the fabrication cost.